Adverb

(en adverb)

In a manner which leaves little question; definitely, clearly.

In a decidedly petulant manner she sat with crossed arms and a frown.

* {{quote-news

, year=2012 , date=April 29 , author=Nathan Rabin , title=TV: Review: THE SIMPSONS (CLASSIC): “Treehouse of Horror III” (season 4, episode 5; originally aired 10/29/1992) citation , page= , passage=In time The Simpsons would, indeed, resort to spoofing such decidedly non-spooktacular fare like E.T and Mr. And Mrs. Smith (both in “Treehouse Of Horror XVIII”) but in 1992 the field was wide-open and the show could cherry-pick the most iconic and beloved fright fare of all time.}}

In a decided or final manner; resolutely.

* 1914 , (Saki), ‘The Lull’, Beasts and Superbeasts :

*:‘We can't,’ said Vera decidedly , ‘we haven't any boats and we're cut off by a raging torrent from any human habitation.’

Adverb

(-)

In a manner that leaves no possibility of doubt; undoubtedly.

* 1871 , , Desperate Remedies , ch. 18:

Now his first suspicion was indubitably confirmed.

* 1907 , ":

The world is indubitably' one if you look at it in one way, but as ' indubitably is it many, if you look at it in another. It is both one and many—let us adopt a sort of pluralistic monism.